1. Field of the Invention
The present invention relates to a carbon nanotube based touch panel, a method for making such touch panel, and a display device adopting such touch panel.
2. Discussion of Related Art
Following the advancement in recent years of various electronic apparatuses, such as mobile phones, car navigation systems and the like, toward high performance and diversification, there has been continuous growth in the number of electronic apparatuses equipped with optically transparent touch panels in front of their respective display devices (e.g., liquid crystal panels). A user of any such electronic apparatus operates it by pressing or touching the touch panel with a finger, a pen, stylus, or a like tool while visually observing the display device through the touch panel. A demand thus exists for such touch panels that are superior in visibility and reliable in operation.
At present, different types of touch panels, including a resistance-type, a capacitance-type, an infrared-type, and a surface sound wave-type, have been developed. Due to the high accuracy and low cost of production of the resistance-type touch panel, this touch panel has become widely used.
A conventional resistance-type touch panel includes an upper substrate, an optically transparent upper conductive layer formed on a lower surface of the upper substrate, a lower substrate, an optically transparent lower conductive layer formed on an upper surface of the lower substrate, and a plurality of dot spacers formed between the optically transparent upper conductive layer and the optically transparent lower conductive layer. The optically transparent upper conductive layer and the optically transparent lower conductive layer are formed of conductive indium tin oxide (ITO).
In operation, an upper surface of the upper substrate is pressed with a finger, a pen, or a like tool, and visual observation of a screen on the liquid crystal display device provided on a back side of the touch panel is provided. The pressing causes the upper substrate to be deformed, and the upper conductive layer thus comes in contact with the lower conductive layer at the position where the pressing occurs. Voltages are applied successively from an electronic circuit to the optically transparent upper conductive layer and the optically transparent lower conductive layer. Thus, the position of the deformation can be detected by the electronic circuit.
The optically transparent conductive layer (e.g., ITO layer) is generally formed by means of ion-beam sputtering, and this method is relatively complicated. Additionally, the ITO layer has poor wearability/durability, low chemical endurance, and uneven resistance over an entire area of the touch panel. Furthermore, the ITO layer has relatively low transparency. All the above-mentioned problems of the ITO layer makes for a touch panel with somewhat low sensitivity, accuracy, and brightness.
What is needed, therefore, is to provide a durable touch panel with high sensitivity, accuracy, and brightness, a method for making such touch panel, and a display device using the touch panel.